Joint International Conference on Long-term Experiments ...

the same plots for several years or decades. The most famous field trials are in
Rothamsted (UK), Halle (Germany) since 1878, Askov (Denmark) since 1894, Poltava
(Ukraine) since 1885 (Sárdi, 2003). The objectives of long-term field trials are to
measure the effectiveness of different fertilizers and types of farmyard manure in
different cropping environments, and to determine the accumulation of various elements
in the soil or the plant. This is the only way to obtain statistically reliable data about the
interaction between the effect of fertilizers and other management techniques (soil
cultivation, crop density, etc.), as well as to set the limit values for the chemical soil
examination (Loch-Nosticzius, 2004).
MATERIAL AND METHODS
Examined samples are from the NLTFT (National Long-Term Field Trials) established
in 1966 and the main objective was to create a uniform trial network that gives points of
reference for the national planning of nutrient demand by involving the different micro-
and macro ecological features of different cropping sites. On the other hand, it provides
a good opportunity to examine the long term effect of mineral fertilizer levels on the
quality characteristics of yield, such as its nutrient status.
The samples used are from Bicsérd, Karcag, Nagyhörcsök, Iregszemcse,
Keszthely, Hajdúböszörmény, Kompolt, Putnok and Mosonmagyaróvár research sites.
The characteristic of these sites according to their soil, agrochemical and climatic
properties was presented by Debreczeni and Debreczeniné (1994) in details. Analysed
winter wheat, maize and pea samples were produced from 1999 to 2003. Different NPK
fertilizer doses and ratios were applied in the experiment. 3 levels of nitrogen (150, 200,
250 kg/ha), 4 levels of phosphorus (200, 100 150 and 200 kg/ha) and 2 levels of
potassium (100 and 200 kg/ha) fertilizer doses were used for winter wheat and maize in
different ratios. For peas, 2 levels of nitrogen (40 and 120 kg/ha), 2 levels of
phosphorus (100 and 150 kg/ha) and 1 level of potassium (100 kg/ha) were applied in
different ratios.
The analysis of the grain samples was performed in the Institute of Food Science,
Quality Assurance and Microbiology of the University of Debrecen, Centre of
Agricultural Sciences. Determination of element contents was performed by Perkin-
Elmer Optima 3300 DV inductively coupled plasma optical emission spectrometer
(ICP-OES) after HNO3 and H2O2 digestion (Kovács et al., 1996; Kovács et al., 1998).
In plant samples undergone wet destruction by HNO3 and H2O2 we determined B,
Ca; Cr; Cu; Fe; K; Mg; Mn; Ni; P; S; Zn content in the dry matter by Perkin Elmer,
Optima 3300 DV, ICP-OES (USA).
Samples were determined by Perkin-Elmer, Optima 3300 DV inductively coupled
plasma emission spectrometer.
RESULTS AND DISCUSSIONS
In our experiment, more than 3000 pea, wheat and corn samples from the NLTFT
(National Long-Term Field Trials) from 1999 to 2003 have been analysed. The database
with over 35000 data allowed for drawing several important conclusions.
The values of the elements represent the value of the plant as raw material for food
or feed when considering the supplementation of the plant with a given element, and
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